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Light Up Halloween 

Make] Projects 

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build, hack, tweak, share, discover,- 

Light Up Halloween 

Written By: Steven Robert Cypherd 



• Hot Glue gun & hot glued) 

• LED (25+) 

• Soldering iron (1) 

• infrared transistor (10+) 

Wire cutter/stripper (1) 

Infrared detector and emitter pair (10+) 


You can use infrared diodes to light up your people when you get close to them. When your 
transmitter activates their detector their lights light up, and their transmitter lights up yours. 
When someone touches your magic spot (your detector) your spot lights up and their thing 
lights up. It is simple and easy to do with transistors. Transistors rule our world. I will show 
you how to light up your people with transistors. 

The first thing you need is parts. Soldering is the best way to make things you can play with. 
RadioShack still sells transistor packs in PNP and NPN varieties. PNP amplifying 
transistors (15-pack) are part #276-1604. RadioShack NPN Transistors (15-pack) are part 
#276-1617. Usually you get about four types of each. I am using PNP transistors in this 
circuit. You can use any of the types of PNP transistors in this pack. Either the 2907 or 3906 
work well here. The next part you need is a good infrared emitter and detector pair. They are 
sold in wavelength (measured in nanometers, nm) and you must match them closely to get 
them to work. 

Out of all the parts I have tried, the infrared 880nm emitter and detector pair are the ones 
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Light Up Halloween 

that worked best for this circuit. They are the little side-shooter two-lead type. The 
transmitter is the 880nm emitter diode. The detector is the photodiode (or phototransistor or 
photo Darlington) in 880nm. Jameco is the best place to get all of the parts. I included the 
PDFs. Use the term 'Infrared' to search for these devices. You only need 
enough power to cross about two inches. All infrared devices work best in the dark. Most 
devices in the range 800nm to 1050nm will work together. The little side shooter two lead 
types have very narrow bream. has packs like RESISTOR, 610 PACK E12-SERIES 1/4W 5% TOLERANCE 
(part #2131039), hook-up wire in a 10-Color Stranded Wire Kit Assortment (part #2130917) 
#135271). For a good soldering station I have the MakerShed's Variable Temperature 
Soldering Station . If you do more types of crafts, a woodburning kit that has a soldering tip 
and hot knife may be a better tool to have. I can't live without my mini toothed pliers, mini 
sharp diagonal cutters, my standard aluminum body X-Acto knife and my mini hot glue gun. 

The circuit is simple. When the detector gets illuminated by a transmitter its resistance 
lowers. This brings the base of the PNP transistor more negative and it turns on and your 
lights light up. The 10K resistor connected between V+ and the base of the PNP transistor 
biases the transistor off. The transmitter can have its own battery and a switch. They use 
the most current when they are on. When you are near to your people switch your 
transmitter on. I made this a 9-volt circuit so it is easy to make and have fun with. 

Because the power supply is 9 volts use a 330-470 resistor on your transmitter. Infrared 
diodes come in different power outputs. See how close you have to be to turn on your lights 
and adjust the resistor's value until the circuit performs the way you want it to. Resistors are 
measured in ohms. 470 is 470 ohms. 1K is 1000 ohms. 10K is 10,000 ohms. You may notice 
that I have no resistors on my LEDs. LEDs are diodes. Diodes in series divide the supply 
voltage between them. Diodes have a forward voltage which can be measured with a digital 
voltmeter set on "Diode." Red LEDs have the lowest forward voltage and yellow and blue 
have the highest. The size and power of the LED will determine its forward voltage. Measure 
them and add up your LEDs to see how many you can put in series with your supply voltage. 
I can put 5 Red LEDs in series on a 9-volt supply. LEDs need about 2 volts to operate. One 
too many LEDs and the lights go out. 

In the A & B circuits the lights turn on when the Detector is hit by a transmitter. In the C & D 
circuits the lights turn off when the Detector is hit by a transmitter. In the B & C circuits the 
transmitter is powered by the transistor when the Detector is hit by a transmitter. All of the 
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Light Up Halloween 

transmitters have switches. I did not have friends to build this for. I should have done more 
work on the C & D circuits before I uploaded the article. It is a very simple circuit. I found 
errors in the ten PDFs and I replaced all of them. Sorry I pushed Fritzing too hard. 

Making the boards is easy. Positive resist boards, positive developer, etchant and exposer 
lights are available at Print the PDF files at 100%. For laser printers print 
transparency sheets on the smooth side and ink-jet on the rough side. You can cut PCBs 
with a light duty metal sheet cutter. 

Etching solution is ammonium persulphate at 250 grams to 1 liter of water. 125 grams 15 
ounces water. Keep etchant warm. Developer is Positive Type P.C. 1 part to 10 parts water. 
1.5 ounces to 15 ounces water. Use plastic trays and bottles. The switch I found on SPDT PC mount standard is 3mm spacing and my board is .1 in. Drill the lower 
two holes 5/34 and the first hole a little bigger .039. Use .035 most holes and .037 for a little 

To work with Fritzing you need electronics knowledge and desk-top publishing experience. 
An example is the Object Label used in all views. Right-click the object and select Show 
Label. Select the object and left-click the label and drag it. Right click the label and select 
Edit, Size, Rotation and Display Details. 

You must get the breadboard and the schematic perfect before you can make a good PCB. 
Avoid "birdcage wires" (Fritzing calls them "rat's nest" wires). Test all circuit paths by 
clicking on a node. Then in the PCB remove any rat's nest wires, rotate and move the parts 
and delete and make new circuit paths. After it looks OK then use Auto Routing. You make 
big changes in the breadboard first then the schematic if you need it and then the PCB. 

To make multiple circuits on one PCB, save your project as somethingAIO. In PCB view 
click the PCB and in Parts set Sticky to unchecked. Click and drag the PCB away from your 
circuit. Set your PCB to the size that you need. A 4"x6" board is 101 .6mm wide and 
152.4mm high. Drag a selection box around your circuit. Let go. Edit Duplicate the circuit 
(Ctrl-D). Wait for the duplicate circuit to show up. Do not click it. Use the arrow keys to 
move your duplicate onto your PCB. Repeat this for each copy. The breadboard and 
schematic will be a mess. Line things up nicely. Save your project. Make an editable PDF. 
Wait for it. Done. I do not put Sticky back on. Watch out for Duplicate errors when making 
multiple copies in one PCB of the same circuit. Look at the labels; they are label plus copy 
number. Do not touch the breadboard or the schematic. 

© Make Projects Page 3 of 5 

Light Up Halloween 
Have fun. 

Step 1 — Light Up Halloween 

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• For masks, toy swords and shields mount your LEDs any way that suits you. Put the 
transmitter on top or right and the detector on the bottom or left. See pictures 

• The transmitter can be another circuit and battery. Turn it off when you are not around your 

• LEDs can be put in a ladder, each with its own resistor to the V+ rail and negative lead to 
the Ground rail. 

• Diodes can be confusing. 
Step 2 

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• If you mount the detector to my board you will have to bend the leads to fit it in. They did 
not have a part that worked for me. 

• My board can be put anywhere. The transmitter, detector and LEDs should be wired to my 

• Any diodes or transistors will work in my board. 

• I did not have friends to build this for. 

© Make Projects 

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Light Up Halloween 

Step 3 

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Light Up Hall Wee n Wring my Circuit Boards 

• I should have done more work on the C & D circuits before I uploaded the article. It is a 
very simple circuit. 

• Interfacing with a Microprocessor 

• A repeater circuit. 

Step 4 

Light Up Halloween 

The Circuits 

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A; Detector hit lights On, Transmitter by Switch 
C: Detector hit lights Off, Transmitter by Trans 

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B: Detector hit fights On. Tranmitter by Trans 
D: Detector hit lights Off, Transmitter by Switch 

• The boards 

Whatever you make, have fun! 

This document was last generated on 201 2-1 2-01 02:45:46 AM. 

© Make Projects 

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